Serotonin-Like Immunoreactivity Reveals Evidence for Centrifugal Fibers and a Distinctive Class of Amacrine Cell in the Skate Retina

Centrifugal innervation of the rat retina

“…5,7-dihydroxytryptamine (5,7-DHT), a non-degradable serotonin analog, is taken up by indoleamine-accumulating neurons through a high-affinity transporter and can be visualized using an immunoreaction against serotonin (Weiler & Schutte, 1985a). If, like in nonmammalian species (Ritchie & Leonard, 1983;Schutte & Weiler, 1988;Schutte & Witkovsky, 1990;Schlemermeyer & Chappell, 1991), indoleamine-accumulating terminals of centrifugal neurons were present in the rat retina, 5,7-DHT should also be retrogradely transported back to the central perikarya which then would stain for serotonin-like immunoreactivity (SLI). 5,7-DHT is taken up by all indoleamine-accumulating neurons and, with lower affinity, also by dopaminergic interplexiform cells (Matsumoto et al, 1992).…”

“…The centrifugal fibers which constitute this efferent pathway have been shown to contain a variety of neuropeptides (Stell et al, 1984;Weiler, 1985;Uchiyama et al, 1988) suggesting a slow, modulatory function, possibly through interaction with other, small molecule neuromodulators such as dopamine (Zucker & Dowling, 1987;Umino & Dowling, 1991). Anatomical evidence predicts an important role, not only for neuropeptides but also for serotonin (5-HT) as a centrifugal transmitter (Ritchie & Leonard, 1983;Schiitte & Weiler, 1988;Schiitte & Witkovsky, 1990;Schlemermeyer & Chappell, 1991). Even though the physiological actions of retinal serotonin are not quite understood, an important role in central control of adaptation and binocular vision has been suggested (Schutte & Weiler, 1988;Schiitte & Witkovsky, 1990).…”

Centrifugal visual system of Crocodylus niloticus: A hodological, histochemical, and immunocytochemical study

“…The antibodies against neuroactive substances or their enzymes of synthesis used in this study have been used previously to identify the cell bodies or fibers of the centrifugal visual system in other vertebrate species: GnRH in teleosts (Munz et al, 1982; Stell et al, 1984, 1987; Oka and Ichikawa, 1990; Oka and Matsushima, 1993); FMRF‐amide in teleosts (Stell et al, 1984, 1987) and anuran amphibians (Wirsig‐Wiechman and Basinger, 1988; Uchiyama et al, 1988); NPY in teleosts (Vecino and Ekström, 1992; Chiba, 1997); TH in anuran amphibians (Schütte and Witkowsky, 1991) and mammals (Simon et al, 2000); 5‐HT in chondrichthyans (Ritchie and Leonard, 1983; Schlemermyer and Chappell, 1991), teleosts (Lima and Urbana, 1998), anurans (Schütte and Witkowsky, 1990), turtles (Schütte and Weiler, 1988), and mammals (Villar et al, 1987; Schütte, 1995; Repérant et al, 2000); GABA in petromyzontiforms (Rio et al, 1992, 1993, 1996; Vesselkin et al, 1996); NOS/NADPH‐d in turtles (Blute et al, 1997; Haverkamp and Eldred, 1998) and birds (Miceli et al, 1999); glutamate in petromyzontiforms (Rio et al, 2002b) and birds (Rio, 1996); and ChAT in birds (Bagnoli et al, 1992; Medina and Reiner, 1994; Miceli et al, 1999). The immunocytochemical and histochemical data of the present study indicate that, of all these substances, only NOS/NADPH‐d, ChAT, and TH are located in the centrifugal visual neurons identified by retrograde labeling with RITC.…”